Dorsal Stainless Surf Thumb Fin Screw and Plate by Surfboard Longboard Bag of 2/Universal NO TOOL REQUIRED: Hand Tighten Against Rubber O-Ring Means No Tools Ever Needed UNIVERSAL FIT: Fits All Standard, FCS, Futures Surfboard Fin Boxes For Longboard, SUP, Inflatable SUP, Single Fin SUPER VALUE: Packs Mean You'll Have An Excuse To Buy More Boards RUST PROOF: 316 Stainless Steel Will Not Rust In Fresh or Salt water. 5% TO CHARITY: Every month we send 1% of our sales to a charity. This month it is El Camino which is improving the health, eternal well being and self-reliance of people living in isolated regions.